/*
 * [New BSD License]
 * Copyright (c) 2011-2012, Brackit Project Team <info@brackit.org>  
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Brackit Project Team nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.brackit.xquery.expr;

import org.brackit.xquery.ErrorCode;
import org.brackit.xquery.QueryContext;
import org.brackit.xquery.QueryException;
import org.brackit.xquery.Tuple;
import org.brackit.xquery.atomic.Bool;
import org.brackit.xquery.xdm.Expr;
import org.brackit.xquery.xdm.Item;
import org.brackit.xquery.xdm.Node;
import org.brackit.xquery.xdm.Sequence;

/**
 * 
 * @author Sebastian Baechle
 * 
 */
public class NodeCmpExpr implements Expr {
	public enum NodeCmp {
		is {
			@Override
			public Bool compare(QueryContext ctx, Node<?> left, Node<?> right)
					throws QueryException {
				return left.equals(right) ? Bool.TRUE : Bool.FALSE;
			}
		},
		preceding {
			@Override
			public Bool compare(QueryContext ctx, Node<?> left, Node<?> right)
					throws QueryException {
				return left.isPrecedingOf(right) ? Bool.TRUE : Bool.FALSE;
			}
		},
		following {
			@Override
			public Bool compare(QueryContext ctx, Node<?> left, Node<?> right)
					throws QueryException {
				return left.isFollowingOf(right) ? Bool.TRUE : Bool.FALSE;
			}
		};

		public abstract Bool compare(QueryContext ctx, Node<?> left,
				Node<?> right) throws QueryException;
	}

	protected final NodeCmp nodeCmp;
	protected final Expr leftExpr;
	protected final Expr rightExpr;

	public NodeCmpExpr(NodeCmp nodeCmp, Expr leftExpr, Expr rightExpr) {
		this.nodeCmp = nodeCmp;
		this.leftExpr = leftExpr;
		this.rightExpr = rightExpr;
	}

	@Override
	public final Sequence evaluate(QueryContext ctx, Tuple tuple)
			throws QueryException {
		return evaluateToItem(ctx, tuple);
	}

	public Item evaluateToItem(QueryContext ctx, Tuple tuple)
			throws QueryException {
		Item left = leftExpr.evaluateToItem(ctx, tuple);
		Item right = rightExpr.evaluateToItem(ctx, tuple);

		if ((left == null) || (right == null)) {
			return null;
		}

		if (!(left instanceof Node<?>)) {
			throw new QueryException(ErrorCode.ERR_TYPE_INAPPROPRIATE_TYPE,
					"Left argument is not a node: %s", left);
		}

		if (!(right instanceof Node<?>)) {
			throw new QueryException(ErrorCode.ERR_TYPE_INAPPROPRIATE_TYPE,
					"right argument is not a node: %s", right);
		}

		return nodeCmp.compare(ctx, (Node<?>) left, (Node<?>) right);
	}

	@Override
	public boolean isUpdating() {
		return ((leftExpr.isUpdating()) || (rightExpr.isUpdating()));
	}

	@Override
	public boolean isVacuous() {
		return false;
	}
}
